Method of shot-hole loading

ABSTRACT

The lower end of a pipe is fitted with a removable cover and driven to the desired depth in an earth formation; an explosive charge having a detonation wire attached thereto is lowered to the bottom of the hole and the detonation wire is then attached at a point just above the top of the pipe to support means that is just large enough to pass through the pipe with just enough frictional engagement to retain the end of the wire above the surface of the ground as the pipe is pulled up over the wire and its support means.

United States Patent [72] Inventor Johnston E. Holzman La .Iolla, Calil. [2]] Appl. No. 688,919 [22] Filed Dec. 7, 1967 [45] Patented July 6, 1971 [73] Assignee Shell Oil Company New York, N.Y.

[54] METHOD OF SHOT-HOLE LOADING 5 Claims, 4 Drawing Figs.

[52] U.S. Cl 102/21, 102/21 .8 [5| 1 Int. Cl F42c 3/06 [50] Field of Search l02/2l 21.6, 21.8; 181/.5 (XC) [56] References Cited UNITED STATES PATENTS 2,755,878 7/1956 Smith 102/21 X 3.l57,ll9 [1964 Porter l02/2L8 FOREIGN PATENTS 703.542 2/1965 Canada l02/2l.8

Primary Examiner-Verlin R. Pendegrass Attorneys-J. H. McCarthy and Freling E. Baker ABSTRACT: The lower end of a pipe is fitted with a removable cover and driven to the desired depth in an earth formation; an explosive charge having a detonation wire attached thereto is lowered to the bottom of the hole and the detonation wire is then attached at a point just above the top of the pipe to support means that is just large enough to pass through the pipe with just enough frictional engagement to retain the end of the wire above the surface of the ground as the pipe is pulled up over the wire and its support means.

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METHOD OF SHOT-HOLE LOADING BACKGROUND OF THE INVENTION This invention relates generally to the art of forming and loading a shot-hole and pertains more particularly to a method of forming a shot-hole and loading an explosive charge having a detonating wire attached thereto through a drill pipe into the shot-hole.

High explosive charges are commonly used as a sound or energy source in seismic prospecting, and as a useful force in the removal of trees and boulders in the building of roads and dams. In both of the above uses, it is often necessary to place the charge some distance below the surface of the ground. Such explosive charges are commonly placed in the ground by drilling a hole and then lowering the charge to the bottom of the hole. However, great difficulty is generally encountered when trying to place the charge in loose unconsolidated soils such as sandy or muddy soils. In such instances, soil from the side of the hole tends to fall into the hole and partially fill it, thus making it difficult or impossible to place the charge at the desired position in the shot-hole. Also, the charge may lodge or hang up on the rough walls of the borehole.

It is the primary object of the present invention to overcome the above and other disadvantages of the prior art methods by providing a method of shot-hole drilling and loading that leaves the shot-hole lined until the explosive charge is placed and then supports the detonating wire above ground while the liner is removed.

It is a further object of the present invention to provide a 1 method of loading explosive charges into a shot-hole through a drill pipe.

It is a still further object of the present invention to provide an improved method of removing drill pipe from a shot-hole over detonating wires while retaining one end of the wires above the ground.

Briefly, the invention consists in driving the lower end of a pipe or tubing, which opens at its lower end as the pipe is withdrawn, to the desired depth in the earth and lowering an explosive charge to the bottom of the hole while retaining one end of the detonation wire above the surface of the ground to which end is attached wire support means which grips the interior of the pipe as it is withdrawn from the hole and retains the detonation wire above the surface of the ground.

A fuller understanding of the objects and advantages of the present invention will become apparent from the following description when read in connection with the accompanying drawings wherein:

.FIG. 1 is a diagrammatic view taken in partial longitudinal cross section of a section of pipe or tubing driven into the earth to form a shot-hole;

FIG. 2 is a diagrammatic view taken in partial longitudinal cross section of the loading of explosive charges in the shothole with wire support means attached to the upper end of the detonator wire;

FIG. 3 is a diagrammatic view taken in partial longitudinal cross section of the pipe or tubing being withdrawn as the wire support means engages it to retain the end of the wire above the surface of the ground; and

FIG. 4 is a diagrammatic view taken in partial longitudinal cross section of the shot-hole finally loaded and ready for shooting.

The preferred method of carrying out the present invention is illustrated in FIGS. 1-4. As illustrated in FIG. 1, the shot hole is formed by driving a string of pipe or tubing 11 into the earth to the depth to which it is desired to placed the explosive charge. The pipe or string may be a single section of pipe or may be a series of sections connected together. The pipe 11, prior to being driven, is fitted at its lower end with a loose fitting plug or driving cap 12 which comes off and remains in the hole leaving the end of the pipe open as it is withdrawn upwardly from the hole. The tubing 11 is driven in any suitable manner but preferably by a sonic vibratory driver or apparatus 13 which is supported in any suitable manner, such as by cable .14 which runs over sheave 15 on boom 16 to a suitable source of power for raising and lowering the driver. Such a vibratory apparatus and its mode of operation is disclosed in U.S. Pat. No. 2,975,846 issued to Mr. A. G. Bodine.

The shot-hole is loaded as shown in FIG. 2 by lowering an explosive charge 17 through the pipe into the shot-hole. The explosive charge is usually made up of a plurality of charges or sticks of dynamite 18 connected together in an end to end fashion with a detonator wire or cord 19 leading out of the hole to be connected to a detonator or source of electric current.

Wire support means 20 is attached in any suitable manner to the wire at a point just above the end of the tubing as shown in FIG. 2. The support means 20 may be attached to the detonation wire at any time before or after the explosive charge has been lowered to the bottom of the shot-hole. The wire support means 20 may be of any suitable construction so long as it is of such size to just pass through the bore of the pipe with just enough frictional engagement to retain it and the detonator wire just above the surface of the ground, as shown in FIG. 3, without pulling the explosive charge 17 from the. bottom of the hole. The support means may be, as illustrated, a spherical mass of resilient material of such diameter as to just pass through the pipe with frictional engagement. Also, it may be of any other suitable shape or material to perform the function. For example, the support means may be a wad of cloth, a sponge, or a body with fingers that flex and extend outward to engage the pipe.

After the support means 20 is attached to the detonator wire 19, the tubing 11 is withdrawn from the shot-hole by pulling apparatus 21 having a drill pipe elevator or other gripping means 22 for gripping the tubing. The drill pipe may be sonically or otherwise vibrated during withdrawal to reduce friction between the pipe and the surrounding soil as it is being drawn upward.

As the lower end of the pipe is pulled from the hole and before the wire support emerges from the end of the pipe, a portion of the detonation wire is accessible between the hole and the end of the pipe, as seen in FIG. 4, so that it may be secured and attached to a suitable detonation means 33. Prior to detonation of the explosive charge the shot-hole is generally filled with either soil or water-to contain the explosion within the hole. If a sonic vibratory device is used to withdraw the pipe the same results is often achieved by collapse of the hole as the pipe is withdrawn. This results from the fluidization of the soil by the sonic energy transmitted from the surrounding soil as the pipe is being withdrawn. 7

It is apparent that other modifications may be made in the present invention which is intended to be limited only by the scope of the appended claims.

I claim as my invention: 1. In a method of loading explosives in a shot-hole the steps of:

lowering an explosive charge to the desired depth in an earth formation having a detonation wire extending therefrom through the bore of a pipe drill to the surface; retaining a portion of the detonation wire above the surface of said formation; attaching to said detonation wire, at a point above the surface of said formation, friction support means of a size to pass through and frictionally engage the interior of said drill pipe to retain the upper end of the detonation wire within the drill pipe at a point above the surface of the ground until said pipe is pulled off said wire support means; withdrawing at least a portion of said drill pipe from the borehole; and whereby the end of said detonation wire is retained above the surface of said formation be said friction support means. 2. In the method of claim 1 including prior to lowering the explosive charge the steps of:

said pipe includes withdrawing said member sonically with a sonic apparatus.

5. A method of forming and loading a shot-hole, said method comprising the steps of:

providing the lower end ofa string of tubing with a driving sonically driving said lower end of said string of tubing to the desired depth in an earth formation;

lowering an explosive charge through the bore of said string of tubing to the desired position near the bottom of said borehole;

extending a detonation core, connected to said explosive charge, through the bore of said tubing to the surface of said formation;

attaching friction support means to said detonation cord at a point above said surface; and

sonically withdrawing said tubing as said friction support means frictionally engages the bore of said tubing and retains said detonation cord above said surface. 

1. In a method of loading explosives in a shot-hole the steps of: lowering an explosive charge to the desired depth In an earth formation having a detonation wire extending therefrom through the bore of a pipe drill to the surface; retaining a portion of the detonation wire above the surface of said formation; attaching to said detonation wire, at a point above the surface of said formation, friction support means of a size to pass through and frictionally engage the interior of said drill pipe to retain the upper end of the detonation wire within the drill pipe at a point above the surface of the ground until said pipe is pulled off said wire support means; withdrawing at least a portion of said drill pipe from the borehole; and whereby the end of said detonation wire is retained above the surface of said formation be said friction support means.
 2. In the method of claim 1 including prior to lowering the explosive charge the steps of: providing one end of said pipe with a loosely fitted cap to close said end; and driving said one end of said pipe to a desired depth in said earth formation.
 3. The method of claim 2 wherein the step of driving said pipe includes driving said member sonically with a sonic apparatus.
 4. The method of claim 1 wherein the step of withdrawing said pipe includes withdrawing said member sonically with a sonic apparatus.
 5. A method of forming and loading a shot-hole, said method comprising the steps of: providing the lower end of a string of tubing with a driving cap; sonically driving said lower end of said string of tubing to the desired depth in an earth formation; lowering an explosive charge through the bore of said string of tubing to the desired position near the bottom of said borehole; extending a detonation core, connected to said explosive charge, through the bore of said tubing to the surface of said formation; attaching friction support means to said detonation cord at a point above said surface; and sonically withdrawing said tubing as said friction support means frictionally engages the bore of said tubing and retains said detonation cord above said surface. 